Flotation machine



June 24, 1941. wElNlG ETAL 2,246,560

FLOTATION MACHINE Filed Aug. 1, 1939 3 Sheets-Sheet l T u 5 T- g, 8 K a1; l \zgfijfi by a. W M m zl {it a I? I /a 16 Fri -I9a 221519 iii Fig.1.14

I N VEN TORS ARTHUR J. Wis/-10 AND RODERICK D; RENNER June 24, 1941- A.J. WEINIG ET AL FLO'I'ATION MACHINE Filed Aug. 1. 19:59

3 Sheets-Sheet 2 INVENTORJ g ARTHUR J WEI/we AND BY RODfR/CK 0. Rams/eATTO EY5 June A. J. WEINIG ETAL. 34 .5 0

FLOTATION MACHINE Filed Aug. 1, 1939 3 Sheets-Shoat 3 ARTHUR J. Wc/maAND Rona-men D. RENNER into the cell and terminate in nozzles 22extend-' ing into a central opening l9a in theupper portion or theimpeller l9. Gas under pressure is delivered to the impeller through theheader 20 and conduits 2| and the volume of gas so admitted iscontrolled through the medium of valves 23.

Some operations will necessitate the introduction of reagent directlyinto the cell in preference to a preliminary conditioning treatment andthe agitating and aerating influences of the machine are utilized formixing the reagent. To this end, a reagent feeder is incorporated in thecell structure and comprises a funnel 26 located above the overflowlevel of the cell and a conduit 28 extending from the funnel into the.opening tile and t ninating in a discharge outlet located in proximityto the discharge nozzles 22.

The impeller it of the present invention has top and bottom plates itlband itc respectively, which are separated by a dividing member orpartition 6% extending from a hub member ile approximately midwaybetween the top and bottom plates.

The dividing member ltd is provided with a central opening 991a adjacentthe hub Ste, and this arrangement permits a. portion of the pulpentering the impeller through the opening Hits to pass below thedividing member into the lowermost discharge compartment B, while theremaining pulp entering through opening i911 passes through the uppercompartment A to the peripheral discharge.

In order to maintain a balanced relation in the distribution of feedentering through open- I central openings i911 and E912, the gasdischarge 4 nozzles 22 terminate adjacent the dividing member 88dbetween the opening i912 and the peripher? of the impeller. By thisarrangement, little, it any, of the discharging gas is drawn into thepulp stream entering compartment B and while some slight amount of gasmay be present in the recirculating pulp by reason of previousentrainment, the volume of pulp traveling through compartment B willcontain at most only minor quantities of undissolved gas.

As a consequence, the streams in the upper and lower chambers closelycorrespond'in composition with the corresponding streams described inthe aforesaid Weinlg application.

In order to insure proper movement of the material through thecompartments A and B, vanes I971. are provided which exert an impellingaction on the material delivered to these compartments and force a rapidmovement thereof toward t periphery.

In such impelling action, the vanes lilh produce a substantial mixingaction as an incident to the impelling movement, with the result thatthe streams brought into intermixture at the periphery have alreadyundergone an appreciable degree of mixing before impinging andpenetrating the static body of pulp beyond the impeller.

As this form of impeller does not utilize a suction action to drawmaterial upwardly from the bottom of the tank into the impeller, it isadvisable to provide the undersurface of the impeller with sweepingvanes l 9m which pump material in through inlet l4 and move any solidstending to collect on the bottom of the tank outwardly toward the wallsof the cell where the full force of the agitative action and peripheralejection acts thereon to move the settled constituents into suspension.

As illustrated in Figure l, the pulp entering through inlet M is causedto travel laterally along the bottom of the tank underneath theimpeller, and beyond the periphery rises under the influence of theagitation, with a portion thereof recirculating back through the opening89a of the impeller. In the impeller, the entering pulp divides into twostreams of different volume. The stream of lesser volume passes downinto compartment B and is caused to travel by the impelling influencesunder the centrifugal influence to a point of discharge at theperiphery. The stream of larger volume enters compartment A and uponentrance is subjected to the mixing influence of gas under pressuredischarged through nozzle 22.

Where reagent is introduced directly into the cell, the reagentdischarge is preferably located as illustrated in Figure 2, with theconduit 25 terminating near the opening Mn and somewhat above the same.The separation and diiferential movement of the two streams occuradjacent the discharge end of conduit 25 with the result that some ofthe reagent passes with the stream entering compartment B, while theremainder is entrapped in the stream moving through compartment A and inthe mixing action in such compartments is brought into thorough andintimate contact with the solid constituents of the pulp therein.

From the foregoing, it will be apparent that compartment B will operatein an underloaded condition as the opening its is not large enough tosatisfy the volume requirements thereof, while compartment A, due to thegreater diameter of the opening lea under the influence of a hydrostaticpressure in thetank, operates lnan overloaded condition. This results inthe formation of a partial vacuum in compartment B, which at theperiphery is satisfied by the downward flow of pulp from compartment A,due to the excess pressure thereof.

The resulting impingement oi the two sqeams causes the gas, solids andliquid, inclusive of reagent, to be brought into thorough and intimateintermixture which is further intensified and developed by reason 01 theresistance offered by the more or 1653 static body of pulp beyond theperiphery to the discharging intermixture.

Thereafter, the impelling force of the agitation and aeration causes thepulp stream to ascend in the tank along theconfinlng walls thereof andthe entrapments oi the flotation reaction rise freely in this ascendingcolumn without impedance from material above. Matter held only insuspension and heavy enough estates to separate from the pulp stream inits upper portion is drawn toward the central portion the cell in whichthere is a descending column of liquid, due to the pumping action of theimpeller and the provision of the central opening I941.

As a consequence, solids separating out of suspension pass into thecentral zone of descent before returning to the agitation zone undergravitational influence, and this withdrawal of settling solids from therising column prevents any impedance thereby which might serve torupture the surface attachments of the bubbles in the flotationreaction.

The material carried to the surface under the aerating influencesbecomes entrapped in the froth and moves across the overflow lip l as aconcentrate.

The form of the invention illustrated in Fi ures 3 and 4 is similar tothat previously described, with the exception that the flotation cell inthis form of invention has its feed inlet at some location other thanthe bottom, and as a consequence, the impeller preferably is located atsome distance from the bottom to provide a larger zone of non-aeratedliquid in the bottom oi the tanlr, which in part is recirculated in itselevatine movement by the asitation oi the inipeller through the openingits and back into the impeller for further treatment.

in the cell illustrated in Figure 3, the inlet and discharge controlhave not been illustrated, but since such cells are in general use andwelllrnown in the art, the details of such control appear unnecessary.It will be understood that some provision will be made ior regulatingthe iiduicl level in the cell and thereby control the depth oi irothwhich passes over the overflow lip it.

in each term of the invention illustrated, the iiotation action is thesame and the circulatory movement determined by the impeller is likewiseis the same in each of these cells. While the tunnel 24 and associatedconduit have only been shown as applied to the form of cell illustratedin Figure 1, it will be understood that such structure may be employedin either form at :cell wherever required.

linthis connection, the feature oi the previously identified Weinigapplication in utilizind means of restraining any vortex tendencies atthe impeller inlet 19a is also utilized in the present invention. i

The form oi! the invention illustrated in Figure 5 illustrates anothermodification of the invention, which is productive of highlybeneflcialresults in certain types of treatments. The cell of this form oi theinvention is substantially the same as the type illustrated in Figure l,with feed to the cell provided by the inlet H at the bottom thereof. Thegrid element ll preferably is omitted and a column 21 encloses shaft I8and the pipes II and 25. i This column has its lower terminus in closeproximity to the top of impeller l9 and is of a diameter large enough toencompass the opening Isa into the upper portion of the impeller.

The upper end of column 21 terminates below the froth bed of the celldetermined by'overflow l5, a'nd in the preferred form, a slidable collar28 is mounted at the upper endof column 21 i to vary'the effectiveelevation thereof.

suitable manner, it has been found convenient to mount it on the bafilestructure 9 either by frictional engagement therewith or through theintermediary of any suitable fastening device and thus insure itsmaintenance during operation in close proximity to the impellerit butout of frictional engagement therewith.

The provision of the column serves to aiford a closer control of thecirculatory movement and restrains any tendency toward cross currentswithin the liquid body, which might otherwise serve to co-mingle theascending and descending streams.

It is intended that the descending stream of material in this form ofthe invention should not return valuable constituents responding to theflotation action, but only so much of the mineral content as is beingmaintained in a state of suspension below the froth bed and is not beingcarried into the froth by the flotation reaction.

The enclosure thus provided for the impeller inlet Illa is subjected toa strong pumping influence induced by the impeller, and it the enclosureis extended into close proximity to the ii'roth bed, a. vortex actionwill result which will dil the ass conduits 2i and reagent conduit 2% asa prove the metallurgical result.

' The form of cell illustrated in Figure 6 is similar to thatillustrated in Figure 3 and has associated therewith a column 21aprovided with a draw down portions of the concentrate. Therefore, theprovision of the collar it is oi importance in providing tor selectivevariation in the elevation of the conduit, to eliminate vorteirtendencies and provide a means for density regulation in the upperportion oi the pulp body. The pipes ti and it serve to restrain anyvorteit tendencies at the upper end of column ill and by proper locationoi the collar it, vorteii conditions can be eiiectively eliminated.

in the upper portion of the pulp body immediately below the froth bed,there will be a zone containing a relatively large percentage of mineralwhich has been partially and incom pletely elevated by the flotationaction and supplemented by the suspending tendencies oi the agitation,which as the operation proceeds, will increase in density.

This zone or increased density impedesto some extent the emcientperformance of the flotation reaction in that minerals ascending underthe action of the gas will not freely penetrate such zone and carry intothe froth, and while some oi the mineral in the zone is further elevatedby the penetration of the gas into the zone, much of the mineral contentis not carried into the froth and consequently passes to the nesttreatment stage with the tailing rather than the concentrate.

By locating the top of the column at or near such zone, the suctioninfluences of the impeller serve to draw in large quantities of suchmineral content and return the same to the impeller for retreatment andsubsequent elevation into the froth. As a consequence, in certaintreatments,

such as the flotation of ores carrying relatively large quantities ofmiddlings product which are imperfectly floated by the normal action,the provision of the column 21 in the cell serves to imcollar 28 forvarying its effective elevation. This column 21a is of a diameter lessthan the diameeter of the opening lfla into the impeller and is mountedin the cell with its'lower terminus in compartment A of impeller i9.

- With this form of column, a portion of the impeller dischargerecirculates back through the opening l9a without rising into the upperportions of the cell and there mixes with pulp delivered through column21a into compartment A and after being subjected to the aeratinginfluences, is again ejected from the impeller in the manner heretoforedescribed.

From the foregoing, it will be apparent that the feed supplied to theimpeller throughthe columns 21 and 21a is split and distributed betweenthe compartments A and B as in the other forms of the invention, and thetreatment of the material within the impeller is, in all essentialrespects, the same as hereinbefore described.

It is also obvious to those skilled in the art that either form ofcolumn 21 or 210 may be applied to any of the various forms bl cellconstruction here illustrated, and the application of the respectiveforms to the various cells in the drawings'is intended only asillustrative and not as being limited to such forms.

While in the forms illustrated herein-the dividing member 19d is shownas'being of the same diameter as the'top and bottom plates lfib and E90respectively, it will be appreciated that whenever desired for anyreason, the dividing member may he of a lesser diameter to induce alore; liminary mixing within the confines oi the impeller beforedischarge of the material across the periphery.

likewise the size of the vanes 89?; may be varied, and while thearrangement illustrated is the preferred form, it is withincontemplation of the invention that vanes of diiierent sizes may bevariably located within the passages A and B,

and in fact, any vanes which serve to exert an impelling action onmatterin the passages may be substituted for those illpstrated herein.

The explanation of the relative diameters of the openings its and i9demonstrates the of fectiveness of therelationship in controlling theamount of material delivered to each of the possages A and B. and itwill be understood that variations. inthe size of such openings may beresorted to to obtain different degrees of mixing and discharge. v 7

Changes and modifications may be availed oi within the spirit and scopeof the hereunto appended claims.

What we claim and desire to secure by Letters Patent is:

1. In separating apparatus, a rotary mixing element comprising upper andlower chambers, separately open at the periphery of the element for theseparate discharge of two currents of pulp into a mixing zone exteriorlyof said periphery, both chambers having central openings in their uppersurfaces to receive pulp in which the element is immersed with one ofsaid openings in their upper surfaces of greater diameter than theother, means for introducing gas in excess of atmospheric pressure intothe pulp at the central opening oi greater diameter, and vanes in thechambers to accelerate outward movement of pulp through the peripheralopenings thereof.

2. In separating apparatus, a rotary mixing element comprising upper andlower. chambers. separately mm at the periphery of the element forthefseparate-discharge of two currents of pulp into amixing zoneexteriorly of said periphery, both chambers having central openings intheir upper surfaces to receive pulp in which the element; is immersedwith the opening oi. the upper chamber of greater diameter than theopening of the lew er chamber, means for intro-- ducing gas-in excess ofatmospheric pressure into the pulp at the central opening of the upperchamber and between the central opening or the lower chamber and itsperiphery, and vanes in the lower chamber to accelerate outward movementof pulp through the peripheral opening rotation for admission of pulp, adividing membe; in the body defining upper and lower chambers therein,and having a central opening for admission of pulp to the lower chamber,means for introducing gas under pressure into pulp entering the upperchamber through the top openlng, andvanes in the lower chamber forimpellent action on the pulp admitted thereto.

4. In aerating apparatus, a rotary hollow body having in its top anopening around its axis of notation for admission of pulp, a dividingmember in the body defining upper and lower chambers therein, and havinga central opening of lesser diameter than the diameter of the topopening, means in the upper chamber at a side of the'opening to thelower chamber for introducing gas under pressure into pulp entering theupper chamber through the top opening, and vanes in the lower chamberfor lmpellent action on the pulp admitted thereto. 5. In separatingapparatus, a rotary mixing element comprising upper and lower chambers,separately open at the periphery of the element for the separatedischarge" of two "currents of pulp into a mixing "zone exteriorly ofsaid periphery, both chambers having upper central omnings to receivepulp inwhich the element is immersed, means emendlng into the upperchamber through itscentral. opening for introducing gas in excess oiatmospheric pressure into the pulp entering therein, and vanes in thelower chamber to accelerate outward'movement of pulp through theperipheral opening thereof.

6. In aerating apparatus, a rotary hollow body having in its top anopening around its axis of rotation for admission of pulp, a dividingmom ber in the-body defining upper and lower chamhers therein, andhaving a central opening of lesser diameter than the diameter of the topopening means in the upper chamber for introduclng gas under pressureinto the pulp in the upper chamber entering therein through the topopening, vanes in the lower chamber for impellent action on the pulpadmitted thereto, and vanes on the underside of the impeller forexerting an lmpellent movement on matter exterlorly thereof.

'7. Froth flotation apparatus, comprising a tank having a feed inlet anda discharge outlet determining a liquid level therein, a rotary impellerin the lower portion of the tank having upper and lower chambersprovided with a central opening for the admimion of pulp underhydrostatic pressure, means for supplying gas under pressure to saidchambers through the central opening of the upper chamber, and a conduithaving its inlet in the pulp body'below the froth bed determined by theoverflow and'positloned to discharge into the central opening of theimpeller.

8. Froth flotation apparatus. comprising a tank having a feed inlet anda discharge outlet determining a liquid level therein, arotary impellerin the lower portion of the tank having upper and lower chambersprovided with a central opening for the admission of pulp underhydrostatic pressure, means for supplying gas under pressure to saidchambers through the central opening of the upper chamber, and a-conduithaving its inlet in the pulp body below the froth bed determined by theoverflow and terminating above and in close proximity to the impeller inencompassing relation to its central opening.

9. Froth flotation apparatus, comprising a tank having a feed inlet anda discharge outlet determining a liquid level therein, a rotary impellerin the lower portion of the tank having upper and lower chambersprovided with a central opening for the admission of pulp underhydrostatic pressure, means for supplying gas under pressure to saidchambers through the central opening of the upper chamber, and a conduithaving its inlet in the pulp body below the froth bed determined by theoverflow and extending into the impeller through the central openingthereof.

10. In aerating apparatus, a rotary hollow body having in its top anopening around its axis of rotation for admission of pulp,-a dividingmember in the body defining upper and lower chambers therein, and havinga central opening for admission of pulp to the lower chamber, means forin-- troducing gas under pressure into pulp entering the upper chamberthrough the top opening, and vanes in each of said chambers forimpellent 80'.- tion on the pulp admitted thereto.

11. Froth flotation apparatus comprising a tank having a feed inlet anda discharge outlet determining a liquid level therein, a rotary impeller in the lower portion of the tank disposed to direct pulp upwardlyalong upright walls of the tank by its centrifugal action, a memberdividing the impeller into superposed compartments, each having acentral intake opening in its upper surface and a peripheral dischargeoutlet, means for introducing gas under pressure into the uppermostcompartment of the impeller, andiconductive means disposed in the tankin a position to collect a middlings product below the liquid level andreturn such product through the central impeller openings for additionalaeration within the confines of the impeller.

12. Froth flotation apparatus comprising a tank having a feed inlet anda discharge outlet determining a liquid level therein, a rotary impellerin the lower portion of the tank disposed to direct pulp upwardly alongupright walls of the tank by its centrifugal action, a member dividingthe impeller into superposed compartments, each having a central intakeopening in its upper surface and a peripheral discharge outlet, meansfor introducing gas under pressure intothe uppermost compartment of theimpeller, means for delivering flotation reagent adjacent the intake ofeach of said compartments, and conductive means disposed in the tank ina position to collect a middlings product below the liquid level andreturn such product through the central impeller openings for additionalaeration within the confines of the impeller.

13. In aerating apparatus, a rotary hollow body having in its top anopening around its axis of rotation for admission of pulp, adividingmember in the body of lesser diameter than the body definingupper and lower chambers therein, and having a central opening foradmission of pulp to the lower chamber, means for introducing gas underpressure into pulp entering the upper chamber through the top opening,and vanes in the lower chamber for impellent action on the pulp admittedthereto.

14. In aerating apparatus. a rotary hollow body having in its top anopening around its axis of rotation for admission of pulp, a dividingmember in the body defining upper and lower chambers therein and havinga central opening for admission of pulp to the lower chamber, means forintroducing gas under pressure into pulp entering the upper chamberthrough the top opening, and conductive means for reagent introductionhaving a discharge outlet terminating within the impeller and above thecentral opening of the dividing member.

15. In aerating apparatus, a rotary hollow body having in its top anopening around its axis of rotation for admission of pulp, a dividingmember in the body defining upper and lower chambei's therein, andhaving a central opening for admission of pulp to the lower chamber,means for introducing gas under pressure into pulp entering the upperchamber through the top opening, and conductive means for reagentintroduction having a discharge outlet terminating within the impellerand above and adjacent the periphery of the central opening of thedividing member.

ARTHUR J. WEINIG.

RODERICK D. RENN'ER.

